Universal bore sight

Abstract

A bore sight ( 10 ) is provided that can be used with many calibers of firearms ( 12 ) to align optical devices such as rifle scopes. The bore sight ( 10 ) has a housing ( 22 ) with a spring loaded arbor ( 26 ) extending from one end thereof. The arbor ( 26 ) has a tapered face ( 32 ) varying in diameter in a range including popular calibers, such as .17 to .50 caliber. The arbor ( 26 ) is inserted in the end ( 20 ) of the barrel ( 18 ) as far as the caliber of the barrel ( 18 ) permits. The arbor ( 26 ) then starts retracting into the housing ( 22 ) against a spring force to allow the magnetic alignment face ( 24 ) of the housing to move into contact with the end ( 20 ) of the barrel to align the bore sight ( 10 ) with the centerline of the bore ( 16 ). A laser ( 30 ) on the bore sight ( 10 ) then projects a laser beam aligned with the bore centerline, allowing alignment of the optical device. Bore sight ( 100 ) forms a second embodiment and does not have an arbor ( 26 ). The bore sight ( 100 ) is hand centered on the end of the barrel and is fixed thereto by the attraction of the magnetic alignment face ( 24 ) to the barrel ( 18 ).

The invention claimed is: 
     
       1. A method for aligning a device to the centerline of a bore of predetermined diameter in a member, the bore having an end with an annular surface lying in a plane generally perpendicular the centerline of the bore, the member being a firearm barrel, comprising the steps of:
 moving a planar surface of a housing of a bore sight into contact with the annular surface at the end of the member, the planar surface lying in a first plane; 
 at least partially inserting an arbor within the bore as far as the diameter of the bore in the member permits, the arbor mounted within the housing, the arbor having a tapered face, the tapered face of the arbor having a diameter varying within a range from at least a first, smaller diameter, to a second, larger diameter, the arbor mounted in the housing for movement along a first direction perpendicular to the first plane and wherein the first, smaller diameter is 0.17 inches and the second, larger diameter is 0.50 inches and wherein the member is a firearm barrel; and 
 retracting the arbor into the housing along the first direction when the diameter of a portion of the arbor face contacting the bore equals the diameter of the bore, aligning the bore sight with the centerline of the bore of the member. 
 
     
     
       2. The method of  claim 1  further comprising the step of activating a laser beam from a laser mounted in the housing, the laser beam aligned along a first direction perpendicular the first plane so that the laser beam is aligned with the centerline of the bore when the bore sight is aligned with the centerline of the bore of the member.